Excavator



(No Model.) I

A. W. ROBINSON.

EXOAVATOR.

Patented Mar. 22, 18 92.

UNITED STATES PATENT E'FFICEQ ARTHUR W. ROBINSON, OF BUCYRUS, OHIO.-

EXCAVATO R.

SPECIFICATION forming part of Letters Patent No. 471,246, dated March22, 1892.

Application filed $eptemher 22, 1891. Serial No. 406,480. (No model.)

To aZZ whom it may concern.-

Be it known that I, ARTHUR W. ROBINSON, a citizen of the United States,and a resident of Bucyrus, in the county of Crawford and State of Ohio,have invented certain new and useful Improvements in Dredges,Excavators, and Like Apparatus, of which the following is aSpecification. 1

My invention relates to improvements in boom-swinging and bucket-liftingdevices in dredging machines, steam -shovels, and the like mechanisms;and it consists in constructing the apparatus in such manner that oneand the same-pair of chains, ropes, or cables perform the dual functionsof lifting the bucket and also of swinging the boom, carrying the bucketeither to the right or to the left, and the apparatus is so constructedthat I do away with the turn-table heretofore frequently used,substituting in place thereof a large idler-wheel placed upon the mast,which serves as a guide simply for the draftchains which come in contactwith its edge, and in my improved apparatus I not only use a single pairof chains or ropes to perform both the lifting and swinging operations,but I as well simplify the winding apparatus, because two drums adaptedto independent rotation are all that are necessary to operate thechains, and my idler-wheel is so arranged in con junction with certainsheaves fixed upon the float or frame of the machine that I can securethe same power and accuracy of operation in the machine throughoutsubstantially one hundred and eighty degrees of swing.

In the drawings hereof, Figure 1 is an elevation of an excavator adaptedto use upon a track of any kind embodying my invention. Fig. 2 is a planof the forward portion of the same as shown in Fig. 1.

A is the base or platform of a car or other device mounted upon Wheels,as shown, if designed to be used upon tracks or otherwise. Of courseafloat or any other structure or platform may be substituted.

B is a mast supported by the frames 0 and D, respectively, in anydesired manner.

F is a boom fulcrumed at F in a suitable shoe G, made rotatable upon theplatform in any of the many well-known ways.

H is a large idler-wheel mounted upon a hub or other suitable bearing I,which may be supported upon a collar J upon the mast, and it rotates ineither direction upon the mast as its axis, turning, of course, in ahorizontal plane, asshown.

KK are two sheaves which are fastenedto any suitable part of the frame.They rotate upon vertical axes. L L are two other sheaves fastened tothe boom E. The lower partof the periphery of the sheaves LL and thesheaves K K are placed in a horizontal plane which, approximately atleast, coincides with that of the edge of the idler H. M M are two othersheaves placed at or near the extremity of the boom. All of thesesheaves and also the idler H are preferably grooved on theirperipheries, so that they may receive and hold the chain or rope N in amanner well-understood.

0 is the dipper or tong frame, and P is the dipper or dredge tongs.

Q is a stay-rod connecting the top of the mast and outer end of theboom, whereby the boom is maintained in its proper position.

The operation is as follows: The chains N N pass at their inner endsaround drums having independent movement, as well understood. Both ofthese drums are reversed and both of the chains running out the dipperor dredge P is lowered to its proper position, the load being receivedby the dipper or dredge. Both of the drums are rotated equally and bothchains lift the load for a short distance. Then, assuming that the loadis to be swung to the right, the right-hand chain is hauled upon, butthe left-hand chain is slackened. This of course is accompanied bysuitable manipulation of the drums over which these chains respectivelypass. The right -hand chain, owing to the presence of the idler H, andaided and directed by the sheaves K and L, over which it passes, haulstangentially upon the boom, and consequently swings it in its direction,or, in other words, to the right, until the right-hand chain entirelyleaves the idler H, the other or left-hand chain of course beingmeantime caused to come in contact with a larger arc of the periphery ofthe idler, and ultimately the parts assume a position substantially atright angles, as seen at a, Fig. 2, to the primary or initial position.It is manifest that after the load has been deposited the parts areeasily drawn back again to their initial position by a reversal of theoperation-27. e., by slackening the right-hand chain and hauling uponthe left-hand onewhich, having an extensive bearing upon theidler-wheel, quickly and easily swings the boom back again. It isapparent that the parts can be swung to the left as well as to theright, and that the extent of movement may be such as desired throughoutsubstantially one hundred and eighty degrees.

I do not broadly claim the method of swingin g the boom by varying thepull of two hoisting-chains, as such is old. As commonly used, however,the spread of the chains necessary to create side draft decreases as theboom swings each way from the central position, becoming zero at rightangles. A device to partially overcome this difliculty has beenheretofore patented. It consists of .a number of sheaves suitably fixedupon a revolving table attached to the base of boom. Bymy improveddevice a uniform side draft is obtained in a simpler and more perfectmanner, and such that the spread of the chains is practically uniformthroughout one hundred and eighty degrees of swing.

I do not limit myself to the details of construction shown anddescribed,because it will be evident to those who are skilled in thisart that certain modifications may be made in the details and yetmyinvention be embodied.

I claim-- 1. The combination of a boom, a mast, an idler, twodipper-hoisting chains, and sheaves which guide the chains upon theidler, substantially as set forth.

2. The combination of a boom, a mast, an idler mounted upon the mast asits axis, two dipper-hoisting chains, and sheaves which guide the chainsupon the idler, substantially as set forth.

3. The combination of a boom, a mast, an

idler supported upon the mast as its axis, four vertically-arrangedsheaves upon the boom, two horizontally-arranged sheaves upon the frameor platform, and two dipper'hoisting chains, the whole being constructedand arranged in such manner that the chains are guided by the sheavesupon the opposite sides of the idler, substantially as set forth.

4. In a dredging apparatus, an idler placed at or near the face of theboom, two dipperhoisting chains, and sheaves constructed and arranged toguide the chains upon the idler, substantially as set forth.

5. The combination, in a dredging apparatus, of a boom, ahorizontally-arranged idler at or near the base of the boom, sheavesupon the boom, and two dipper-hoisting chains in the same horizontalplane as the idler, sub stantially as set forth.

6. The eombination,in a dredging-machine,

of a boom, a horizontally-arranged idler at or near the base of theboom, two dipper-hoisting, chains, two sheaves upon the boom, and twoupon the frame or platform of the apparatus, all of them arranged insubstantially the same horizontal plane, substantially as set forth.

7. The combination, in a dredging apparatus, of two chains eachconnected at one end with the dipperor bucket and atthe other withindependently-moving drums and which chains are located at oppositesides of the boom, said boom itself,an idlerat or near the base of theboom, and sheaves to guide the chains, respectively, at opposite sidesof the idler, substantially as set forth.

Signed at Bucyrus, in the county of Crawford and State of Ohio, this15th day of July,

ARTHUR W. ROBINSON.

lVitnesses:

E. K. SVVIGART, J. M. l\IILL1\'[AN.

